The preparation of CeF3 nanocluster capped with oleic acid by extraction method and application to lithium grease

CeF3 nanocluster surface-capped with oleic acid (coded as OA-CeF3) were prepared using extraction method. The resulting OA-CeF3 nanocluster was characterized by means of transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transformation infrared spectrometry (FTIR), and X-ray photoelectron spectroscopy (XPS). The effect of the OA-CeF3 nanocluster as an additive in synthetic lithium grease was investigated using a four-ball friction and wear tester. It was found that the as-prepared OA-CeF3 nanocluster had a broad size distribution, with the average diameter to be about 20 nm, which was confirmed by both the XRD and TEM analytical results. The oleic acid as the capping agent was chemically bonded to the CeF3 nanocores via strong chemical interaction. The OA-CeF3 nanocluster as the additive led to an obvious improvement in the antiwear and extreme pressure properties of the synthetic lithium grease. However, the OA-CeF3 nanocluster as the additive had little effect on the friction-reducing behavior of the lithium grease.